HMG box proteins bind to four-way DNA junctions in their open conformation.
The HMG box is an 80 amino acid domain found in a variety of eukaryotic chromosomal proteins and transcription factors. Binding to DNA is associated with recognition of structural distortion or manipulation of DNA structure. All the HMG box domains bind to four-way DNA junctions, which must therefore present some feature that is common to the binding targets of this wide variety of proteins. Since the four-way junction can itself adopt a variety of structures depending upon conditions, it is important to determine in which form it exists in complexes with HMG boxes. We find that a single HMG box domain is bound exclusively to the open square form of the junction and that conditions that stabilize the stacked X structure significantly lower affinity for the HMG box. We suggest that the HMG domain binds to one arm of the junction in the minor groove at the point of strand exchange and we present a model for the structure of the complex.
P-ohler
J R
JR
CRC Nucleic Acid Structure Research Group, Department of Biochemistry, The University of Dundee, Dundee DD1 4HN, UK.
Norman
D G
DG
Bramham
J
J
Bianchi
M E
ME
Lilley
D M
DM
D000818:Animals; D002352:Carrier Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D004247:DNA / Q000737:chemistry / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D015870:Gene Expression / Q000235:genetics; D006609:High Mobility Group Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D046911:Macromolecular Substances; D008274:Magnesium / Q000494:pharmacology; D058619:Maltose-Binding Proteins; D015335:Molecular Probes; D009690:Nucleic Acid Conformation; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D013941:Thymine / Q000032:analysis / Q000737:chemistry
D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D006609:High Mobility Group Proteins; D046911:Macromolecular Substances; D058619:Maltose-Binding Proteins; D015335:Molecular Probes; D011993:Recombinant Fusion Proteins; D004247:DNA; D008274:Magnesium; D013941:Thymine